/*
 * Copyright 2002-2012 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.jdbc.datasource.embedded;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.apache.derby.impl.io.VFMemoryStorageFactory;
import org.apache.derby.jdbc.EmbeddedDriver;

import javax.sql.DataSource;
import java.io.File;
import java.io.IOException;
import java.sql.SQLException;
import java.util.Properties;

/**
 * {@link EmbeddedDatabaseConfigurer} for the Apache Derby database.
 *
 * @author Oliver Gierke
 * @author Juergen Hoeller
 * @since 3.0
 */
final class DerbyEmbeddedDatabaseConfigurer implements EmbeddedDatabaseConfigurer {

    private static final Log logger = LogFactory.getLog(DerbyEmbeddedDatabaseConfigurer.class);

    private static final String URL_TEMPLATE = "jdbc:derby:memory:%s;%s";

    // Error code that indicates successful shutdown
    private static final String SHUTDOWN_CODE = "08006";

    private static final boolean IS_AT_LEAST_DOT_SIX = new EmbeddedDriver().getMinorVersion() >= 6;

    private static final String SHUTDOWN_COMMAND =
            String.format("%s=true", IS_AT_LEAST_DOT_SIX ? "drop" : "shutdown");

    private static DerbyEmbeddedDatabaseConfigurer INSTANCE;


    /**
     * Get the singleton {@link DerbyEmbeddedDatabaseConfigurer} instance.
     *
     * @return the configurer
     * @throws ClassNotFoundException if Derby is not on the classpath
     */
    public static synchronized DerbyEmbeddedDatabaseConfigurer getInstance() throws ClassNotFoundException {
        if (INSTANCE == null) {
            // disable log file
            System.setProperty("derby.stream.error.method",
                    OutputStreamFactory.class.getName() + ".getNoopOutputStream");
            INSTANCE = new DerbyEmbeddedDatabaseConfigurer();
        }
        return INSTANCE;
    }

    private DerbyEmbeddedDatabaseConfigurer() {
    }

    public void configureConnectionProperties(ConnectionProperties properties, String databaseName) {
        properties.setDriverClass(EmbeddedDriver.class);
        properties.setUrl(String.format(URL_TEMPLATE, databaseName, "create=true"));
        properties.setUsername("sa");
        properties.setPassword("");
    }

    public void shutdown(DataSource dataSource, String databaseName) {
        try {
            new EmbeddedDriver().connect(
                    String.format(URL_TEMPLATE, databaseName, SHUTDOWN_COMMAND), new Properties());
        } catch (SQLException ex) {
            if (!SHUTDOWN_CODE.equals(ex.getSQLState())) {
                logger.warn("Could not shutdown in-memory Derby database", ex);
                return;
            }
            if (!IS_AT_LEAST_DOT_SIX) {
                // Explicitly purge the in-memory database, to prevent it
                // from hanging around after being shut down.
                try {
                    VFMemoryStorageFactory.purgeDatabase(new File(databaseName).getCanonicalPath());
                } catch (IOException ex2) {
                    logger.warn("Could not purge in-memory Derby database", ex2);
                }
            }
        }
    }

}
